This invention relates generally to methods of, and apparatuses for accurately monitoring the properties of spray water used in a continuous caster system. As described for example in U.S. Pat. Nos. 7,549,397, 8,220,525, and 8,066,054, continuous casting is a method of converting molten metal into semi-finished metal products such as billets, blooms, or slabs, and is useful for high volume and continuous operations. Typically in continuous casting, molten metal is collected in a special trough called a tundish and is then passed at a precisely controlled rate into a primary cooling zone. In the primary cooling zone the molten metal comes into contact with a solid mold (often made of copper and often water/liquid cooled). The solid mold draws heat from the molten metal causing a solid “skin” of metal to form around a still liquid core. This solid clad liquid metal is referred to as a strand.
Usually the strand is then passed to a secondary cooling zone in which the stand is positioned within a spraying chamber where a liquid cooling medium (often water) is sprayed against the strand to further cool the metal. Examples of spraying technology used in spraying chambers are described in U.S. Pat. Nos. 4,699,202, 4,494,594, 4,444,495, 4,235,280, 3,981,347, 6,360,973, 8,216,117, and 7,905,271. While being sprayed the strand is also supported by rollers which prevent the solid walls of the strand from suffering breakouts (the leakage of liquid metal out from cracks in the strand's solid skin) caused by ferro-static pressure (pressure caused by the different properties of the moving solid and liquid metal pressing against each other). The more solid strand is then passed on to subsequent cooling, shaping, and/or cutting steps.
As detailed in U.S. Pat. Nos. 7,799,151 and 4,024,764, proper casting operations require precise control and adjustment over all of the components used. Of particular importance is fine control over the spraying of the cooling medium at the spray. Scientific paper: Comparison of Impact, Velocity, Drop Size and Heat Flux to Redefine Nozzle Performance in the Caster by Kristy Tanner Presented at American Iron and Steel Technology Conference (2004) describes how such factors as droplet size, spray density distribution, and droplet velocity are all crucial in proper cooling techniques. This is because they affect the formation of a steam layer or vapor layer on the strand which affects heat flux distribution and localized cooling of the strand (all of which impact the overall quality of the resulting metal). Knowing the chemical composition of the droplets can be used to determine these factors as well as give insight into corrosion and cooling rates. This however requires real time knowledge of the exact properties of the cooling medium present in the spraying chamber. Such understanding however is complicated by the nature of the spraying chamber.
Often a number of particles can end up in contact with the cooling medium and they in turn change the properties of the medium and make measurement of those properties difficult. For example lubricants (like mold powder such as that described in U.S. Pat. No. 6,315,809) are often placed on the solid mold, which are pulled into the secondary cooling zone by the strand. Once there the lubricants can react with super-hot water to form complex chemistries including highly reactive hydrofluoric acid. This, along with the intense pressure and temperature can cause additional particles to form from corrosion of bits of metal from the strand or from the pipes or walls of the spraying chamber itself. This in turn fills any collected cooling medium used for sampling with particles that can block piping used for collecting sprayed medium, or which can damage the monitors themselves.
It is therefore useful and desirable to provide methods and apparatus to separate solid particles from condensed liquid cooling medium used in a continuous casting operation. The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “Prior Art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 CFR §1.56(a) exists.